Yokoshima Masamichi was born in Tokyo. He started the violin at the age of five. Yokoshima graduated from Toho Gakuen Music High School and Toho Gakuen School of Music. He won First Prize, and the Uzuka Prize, Togi Prize and NHK Prize at the 62nd Student Music Concours of Japan. Yokoshima has studied under Hori Masafumi, Kubo Ryoji, Iida Yoshie, and Kusano Reiko. Currently he is a member of the NHK Symphony Orchestra.